Composite sandwich panels are used to construct buildings. These panels can include insulative materials and therefore find particular application in constructing cool stores and large scale fridges.
The panels are formed from at least one, and preferably two, sheets of a casing material. The casing material is generally aluminum, steel, or other hard resilient materials.
An insulation material such as a polyurethane foam is injected into a gap between the sheets of casing material. The foam expands to fill the gap and a curing process is used to set the foam.
Locking element in the form of cooperating cam-lock halves are secured in the sandwich panels. Each half is configured such that in use it interacts with a corresponding locking half on an adjacent sandwich panel. Accordingly, the interaction of the cam-lock elements secures adjacent panels together.
One common method to manufacture composite sandwich panels uses a discontinuous process. The sheets of casing material are first cut to a length necessary to form the desired length of a sandwich panel. The sheets of material are then deformed using a roller press. The deformation ensures that the sandwich panel will have a shape and configuration to facilitate adjacent panels interlocking.
Two sheets of deformed casing material are then inserted into a curing mould.
Locking elements are then secured to the mould. A plurality of male locking elements are secured along the mould at one edge of the sheets of casing material. A plurality of female locking elements are secured to the mould along an edge of the casing materials that is distal to the male locking elements. The position of the locking elements relative to the sheets of casing material is selected so that the finished sandwich panel will have a locking element in a position in which it can engage with another locking element on an adjacent sandwich panel. A polyurethane foam is then injected into a gap between the sheets of casing material.
The mould is then used to cure the polyurethane foam. This secures the locking element and sheets of casing material relative to each other, thereby forming the composite sandwich panel.
The insertion and positioning of locking elements is an important step. Incorrect positioning of the locking elements in a panel would result in the locking elements of two laterally adjacent sandwich panels being unable to engage with each other. Accordingly, the process has traditionally been performed manually. As a result, the production of composite sandwich panels is a labour intensive process.
Furthermore, the necessity for accurate placement of the locking elements hinders efficient manufacturing of composite sandwich panels.
The discontinuous manufacture of composite sandwich panels also hinders the efficient manufacturing of panels. For instance, in discontinuous processes it is difficult to adjust the process to produce panels of different dimensions.
Yet a further problem with the discontinuous manufacture of composite sandwich panels is that this is a slow process. The time to manufacture each panel includes the positioning of the sheet materials, the positioning of the locking element halves, the insertion of the insulation material, and curing time. The set up times are significant. Furthermore, the time to remove a cured composite sandwich panel from the mould is a further down time. In fact, the time to manufacture one composite sandwich panel can often exceed 40 minutes.
There are a number of hindrances to using a continuous process to manufacture composite sandwich panels. A significant problem arises from the need to accurately position locking elements within the sandwich panels. All previous attempts to implement a continuous process to manufacturing composite sandwich panels have focused on using the same steps as in discontinuous processes. However, the methods do not work as the securing the locking element halves to the mould prohibits or hinders a constant feed of casing material into the mould.
Accordingly, there is a need for an improved method of producing insulated sandwich panel building elements.
Alternatively, it is an object of the present invention to address the forgoing problems, or provide the public with a useful choice.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
Throughout this specification, the word “comprise”, or variations thereof such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.